Sheet conveying device and image processing apparatus

ABSTRACT

A sheet conveying device includes a tray, an elevating mechanism, a conveyance roller, and a resistance member. The tray stacks a plurality of sheets. The elevating mechanism lifts and lowers the tray in the stacking direction of a plurality of sheets. The conveyance roller conveys the plurality of sheets in the conveyance direction from the upper side in the stacking direction. The resistance member comes into contact with the leading ends of the plurality of sheets in the conveyance direction. The resistance member imparts a sliding resistance larger than that of the sheet stacking surface of the tray to the leading ends of the plurality of sheets that are lifted and lowered by the elevating mechanism.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of application Ser. No. 16/984,309filed on Aug. 4, 2020, the entire contents of which are incorporatedherein by reference.

FIELD

Embodiments described herein relate generally to a sheet conveyingdevice and an image processing apparatus.

BACKGROUND

The image processing apparatus includes a sheet conveying device thatcan stack a plurality of sheets. The plurality of sheets may have highadhesion in the stacking direction due to, for example, the storageenvironment. If the adhesion between the sheets is too high, doublefeeding is likely to occur when the sheets are conveyed.

In order to prevent double feeding, the user may have to separatemultiple sheets before placing the sheets on the sheet conveying device.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a configuration example of animage processing apparatus according to a first embodiment;

FIG. 2 is a schematic perspective view showing a manual feed tray(lifted position);

FIG. 3 is a schematic perspective view showing the external appearanceof the manual feed tray;

FIG. 4 is a schematic perspective view showing the manual feed tray(first lowered position);

FIG. 5 is a schematic perspective view showing a configuration exampleof an elevating mechanism;

FIG. 6 is a schematic diagram of a cross section showing the manual feedtray at the first lowered position of an elevating plate;

FIG. 7 is a schematic diagram of a cross section showing the manual feedtray at the lifted position of the elevating plate;

FIG. 8 is a schematic diagram of a cross section showing an example of amanual feed unit;

FIG. 9 is a schematic diagram of the IX view in FIG. 8 ;

FIG. 10 is a schematic diagram of a cross section taken along line X-Xin FIG. 9 ;

FIG. 11 is a block diagram of a control system;

FIG. 12 is a flowchart of an image forming operation by manual sheetfeeding;

FIG. 13A is an operation explanatory diagram of the manual feed tray;

FIG. 13B is an operation explanatory diagram of the manual feed tray;

FIG. 13C is an operation explanatory diagram of the manual feed tray;

FIG. 14 is a schematic diagram of a cross section of a sheet conveyingdevice according to a second embodiment;

FIG. 15 is a schematic perspective view of the sheet conveying device;

FIG. 16 is a schematic perspective view of an elevating mechanism in animage processing apparatus according to the second embodiment;

FIG. 17 is a block diagram of a control system;

FIG. 18 is an operation explanatory diagram of a tray detection sensor;

FIG. 19 is a flowchart of an image forming operation by cassette sheetfeeding;

FIG. 20A is an operation explanatory diagram of the sheet conveyingdevice;

FIG. 20B is an operation explanatory diagram of the sheet conveyingdevice;

FIG. 21 is a schematic diagram of a cross section of a sheet conveyingdevice (first lowered position) according to a third embodiment;

FIG. 22 is a block diagram of a control system in an image processingapparatus of the third embodiment;

FIG. 23 is a schematic diagram of a cross section of the sheet conveyingdevice (second lowered position) of the third embodiment;

FIG. 24 is a flowchart of an image forming operation by cassette sheetfeeding;

FIG. 25A is a schematic diagram of a cross section showing amodification (first modification) of a resistance member in the sheetconveying device of each embodiment;

FIG. 25B is a schematic diagram of a cross section showing amodification (second modification) of the resistance member in the sheetconveying device of each embodiment;

FIG. 25C is a schematic diagram of a cross section showing amodification (third modification) of the resistance member in the sheetconveying device of each embodiment;

FIG. 25D is a schematic diagram of a cross section showing amodification (fourth modification) of a regulation plate in the sheetconveying device of each embodiment;

FIG. 25E is a schematic diagram of a cross section showing amodification (fifth modification) of the resistance member in the sheetconveying device of each embodiment;

FIG. 25F is a schematic diagram of a modification (sixth modification)of the resistance member in the sheet conveying device of the firstembodiment as viewed from the conveyance direction;

FIG. 25G is a schematic diagram of a modification (seventh modification)of the resistance member in the sheet conveying device of the firstembodiment as viewed from the conveyance direction; and

FIG. 26 is a schematic diagram of a cross section of a sheet conveyingdevice according to a modification (eighth modification) of the secondembodiment.

DETAILED DESCRIPTION

In general, according to one embodiment, the sheet conveying deviceincludes a tray, an elevating mechanism, a conveyance roller, and aresistance member. The tray stacks a plurality of sheets. The elevatingmechanism lifts and lowers the tray in the stacking direction of aplurality of sheets. The conveyance roller conveys the plurality ofsheets in the conveyance direction from the upper side in the stackingdirection. The resistance member comes into contact with the leadingends of the plurality of sheets in the conveyance direction. Theresistance member imparts a sliding resistance larger than that of thesheet stacking surface of the tray to the leading ends of the pluralityof sheets that are lifted and lowered by the elevating mechanism.According to another embodiment, sheet conveying method involves liftingand lowering a tray configured to accommodate a stack of a plurality ofsheets in a stacking direction of the plurality of sheets using anelevating mechanism; conveying one sheet at a time from the plurality ofsheets in the conveyance direction from the upper side in the stackingdirection; and contacting a resistance member with a leading end of theplurality of sheets in the conveyance direction and imparting a slidingresistance larger than a sliding resistance of a sheet stacking surfaceof the tray to the leading ends of the plurality of sheets that arelifted and lowered by the elevating mechanism.

Hereinafter, a sheet conveying device and an image processing apparatusaccording to embodiments will be described with reference to thedrawings. In the following respective drawings, the same orcorresponding components are denoted by the same reference numeralsunless otherwise specified. Examples of the configurations correspondingto each other include configurations having plane symmetry with respectto an appropriate plane.

First Embodiment

The sheet conveying device and the image processing apparatus accordingto the first embodiment will be described.

FIG. 1 is a schematic diagram showing a configuration example of animage processing apparatus according to an embodiment.

As shown in FIG. 1 , an image processing apparatus 100 according to thepresent embodiment includes a control panel 1, a scanner unit 2, aprinter unit 3, a sheet supply unit 4, a conveyance unit 5, a manualfeed unit 10 (sheet conveying device), and a control circuit 60.

Hereinafter, when referring to the relative position in the imageprocessing apparatus 100, the Xp direction, the Xm direction, the Ypdirection, the Ym direction, the Zp direction, and the Zm directionshown in the drawing may be used. The Xp direction is a direction fromleft to right when standing in the front of the image processingapparatus 100 (on the front side of the paper surface of FIG. 1 ). TheXm direction is opposite to the Xp direction. The Yp direction is adirection from the back surface to the front surface of the imageprocessing apparatus 100. The Ym direction is opposite to the Ypdirection. The Zp direction is a vertically upward direction. The Zmdirection is a vertically downward direction. When the directions of theXp (Yp, Zp) direction and the Xm (Ym, Zm) direction do not matter orboth directions are included, they are simply referred to as the X (Y,Z) direction.

Hereinafter, a plane having a normal line in the X direction is called aYZ plane, a plane having a normal line in the Y direction is called a ZXplane, and a plane having a normal line in the Z direction is called anXY plane. The ZX plane is parallel to the sheet S conveyance directiondescribed later in the image processing apparatus 100. The XY plane is ahorizontal plane.

The control panel 1 operates the image processing apparatus 100 by auser's operation.

The scanner unit 2 reads the image information of the object to becopied based on brightness and darkness of light. The scanner unit 2outputs the read image information to the printer unit 3.

The printer unit 3 forms an image on a sheet S based on imageinformation from the scanner unit 2 or the outside.

The printer unit 3 forms an output image (toner image) with a developercontaining toner. The printer unit 3 transfers the toner image onto thesurface of the sheet S. The printer unit 3 applies heat and pressure tothe toner image on the surface of the sheet S to fix the toner image onthe sheet S.

The sheet supply unit 4 supplies the sheets S one by one to the printerunit 3 at the timing when the printer unit 3 forms a toner image.

The sheet supply unit 4 includes a plurality of sheet feed cassettes 20and a plurality of cassette sheet feed units 21.

The plurality of sheet feed cassettes 20 accommodate sheets S of varioussizes. In the example shown in FIG. 1 , the plurality of sheet feedcassettes 20 are provided in three stages.

The plurality of cassette sheet feed units 21 are arranged above theends of each sheet feed cassette 20 in the Xp direction. Each cassettesheet feed unit 21 includes a pickup roller 212 (conveyance roller), asheet feed roller 211, and a separation roller 213.

The pickup roller 212 conveys the sheet S required for image formationfrom the sheet feed cassette 20 to the nip portion between the sheetfeed roller 211 and the separation roller 213. The pickup roller 212 isan example of a conveyance roller that conveys the plurality of sheets Sin the conveyance direction from the upper side in the stackingdirection.

The sheet feed roller 211 conveys the sheet S conveyed to the nipportion to the conveyance unit 5.

The separation roller 213 separates one sheet S when a plurality ofsheets S are conveyed.

The conveyance unit 5 includes conveyance rollers 23 and registrationrollers 24. The conveyance unit 5 conveys the sheet S supplied from thesheet supply unit 4 to the registration rollers 24.

The registration rollers 24 convey the sheet S at the timing when theprinter unit 3 transfers the toner image onto the sheet S.

The conveyance rollers 23 abut the leading end of the sheet S in theconveyance direction against the nip N of the registration rollers 24.The conveyance rollers 23 adjust the position of the leading end of thesheet S in the conveyance direction by bending the sheet S.

The registration rollers 24 align the leading end of the sheet Sdelivered from the conveyance roller 23 at the nip N. Further, theregistration roller 24 conveys the sheet S to a transfer unit 28 sidedescribed later.

The conveyance unit 5 has conveyance paths 301, 302, 303, and 304. Theconveyance paths 301, 302, 303, and 304 will be described after theother configurations of the printer unit 3 are described.

The printer unit 3 includes a plurality of image forming units 25, aplurality of exposure units 26, an intermediate transfer belt 27, thetransfer unit 28, a fixing device 29, and a transfer belt cleaning unit35.

Four of the plurality of image forming units 25 are arranged in the Xpdirection.

Each of the plurality of image forming units 25 forms a toner image tobe transferred onto the sheet S on the intermediate transfer belt 27.

Each of the plurality of image forming units 25 includes aphotosensitive drum 7. The plurality of image forming units 25 formyellow, magenta, cyan, and black toner images on the respectivephotosensitive drums 7.

A charger, a developing device 8, a primary transfer roller, a cleaningunit, and a charge eliminator are arranged around each photosensitivedrum 7. The primary transfer roller faces the photosensitive drum 7. Theintermediate transfer belt 27 is sandwiched between the primary transferroller and the photosensitive drum 7. An exposure unit 26 is arrangedbelow the charger and the developing device 8.

A toner cartridge 33 is arranged above each image forming unit 25. Eachtoner cartridge 33 stores a different color of toner. The four tonercartridges 33 contain yellow, magenta, cyan, and black toners,respectively.

The toner in each toner cartridge 33 is supplied to the image formingunit 25 below each by a toner replenishing pipe (not shown).

The exposure section 26 irradiates the surface of each chargedphotosensitive drum 7 with laser light. The emission of the laser lightis controlled based on the image information. The exposure unit 26 canalso be configured to emit LED light instead of laser light. In theexample shown in FIG. 1 , the exposure unit 26 is arranged below theplurality of image forming units 25.

Image information corresponding to yellow, magenta, cyan, and black issupplied to the exposure unit 26.

The exposure unit 26 forms an electrostatic latent image on the surfaceof each photosensitive drum 7, based on the image information.

The intermediate transfer belt 27 is an endless belt. Tension is appliedto the intermediate transfer belt 27 by a plurality of rollers abuttingon the inner peripheral surface. The intermediate transfer belt 27 isstretched flat. The inner peripheral surface of the intermediatetransfer belt 27 comes into contact with a support roller 281 at themost distant position in the Xp direction in the stretching direction.The inner peripheral surface of the intermediate transfer belt 27 comesinto contact with a transfer belt roller 32 at the most distant positionin the Xm direction in the stretching direction.

The support roller 281 forms a part of the transfer unit describedlater. The support roller 281 guides the intermediate transfer belt 27to the secondary transfer position.

The transfer belt roller 32 guides the intermediate transfer belt 27 tothe cleaning position.

On the lower surface side of the intermediate transfer belt 27 in thedrawing, each image forming unit 25 except the primary transfer rolleris arranged in the Xp direction. The image forming units 25 are arrangedin a region between the transfer belt roller 32 and the support roller281 with a space therebetween.

A transfer bias is applied to the primary transfer roller of each imageforming unit 25 when the toner image reaches the primary transferposition. Each primary transfer roller transfers the toner image on thesurface of each photosensitive drum 7 onto the intermediate transferbelt 27 (primary transfer).

On the intermediate transfer belt 27, the transfer unit 28 is arrangedat a position that is closest to the image forming unit 25 in the Xpdirection.

The transfer unit 28 includes the support roller 281 and a secondarytransfer roller 282. The secondary transfer roller 282 and the supportroller 281 sandwich the intermediate transfer belt 27. The positionwhere the secondary transfer roller 282 and the intermediate transferbelt 27 contact each other is the secondary transfer position.

The transfer unit 28 transfers the charged toner image on theintermediate transfer belt 27 onto the surface of the sheet S at thesecondary transfer position. The transfer unit 28 applies a transferbias to the secondary transfer position. The transfer unit 28 transfersthe toner image on the intermediate transfer belt 27 to the sheet S bythe transfer bias.

The fixing device 29 applies heat and pressure to the sheet S. Thefixing device 29 fixes the toner image transferred to the sheet S by theheat and pressure. The fixing device 29 is arranged above the transferunit 28.

The transfer belt cleaning unit 35 faces the transfer belt roller 32.The transfer belt cleaning unit 35 sandwiches the intermediate transferbelt 27. The transfer belt cleaning unit 35 scrapes off the toner on thesurface of the intermediate transfer belt 27.

Conveyance paths 301 and 302 for conveying the sheet S from the lowerside to the upper side are formed in this order between the registrationrollers 24 and the transfer unit 28 and between the transfer unit 28 andthe fixing unit 29. A conveying path 303 for horizontally dischargingthe sheet S is formed between the fixing device 29 and the sheetdischarge port.

Above the fixing device 29, a conveyance direction switching unit 31that switches the conveyance direction of the sheet S is provided.

A conveyance path 304 that conveys the sheet S from the conveyancedirection switching unit 31 on the fixing device 29 to the registrationrollers 24 is formed inside the printer unit 3 on the Xp direction sidefrom the conveyance paths 301 and 302. The conveyance path 304 is used,for example, to reverse the sheet S having an image formed on thesurface thereof and feed the sheet to the registration rollers 24 whenperforming double-sided printing.

Each of the conveyance paths 301, 302, 303, and 304 includes conveyanceguide units that face each other with the sheet S sandwichedtherebetween, and a conveyance roller that is provided as necessary.

The manual feed unit 10 supplies the sheet S on which an image is formedto the printer unit 3. The manual feed unit 10 is an example of a sheetconveying device.

The manual feed unit 10 includes a manual sheet feed unit 11, a manualfeed tray 12, and an elevating mechanism 40.

The manual feed tray 12 is rotatable around an axis extending in the Ydirection. When the manual feed tray 12 is used, as indicated by thesolid line, the manual feed tray 12 is rotated clockwise when viewedfrom the Ym direction and opened. Sheets S of various sizes can beplaced on the opened manual feed tray 12.

When the manual feed tray 12 is not used, the manual feed tray 12 isaccommodated on the side of the printer unit 3 in the Xp direction bybeing rotated counterclockwise in the drawing, as indicated by the chaindouble-dashed line.

The manual sheet feed unit 11 separates and feeds the sheet S placed onthe manual feed tray 12 and conveys the sheet S toward the registrationrollers 24.

The manual sheet feed unit 11 includes a pickup roller 112 (conveyanceroller), a sheet feed roller 111, and a separation roller 113.

The pickup roller 112, the sheet feed roller 111, and the separationroller 113 have the same configurations as the pickup roller 212, thesheet feed roller 211, and the separation roller 213 in the cassettesheet feed unit 21.

The pickup roller 112 is an example of a conveyance roller that conveysthe plurality of sheets S in the conveyance direction from the upperside in the stacking direction.

Next, the detailed configuration of the manual feed tray 12 will bedescribed.

FIG. 2 is a schematic perspective view showing a manual feed tray(lifted position) of the image processing apparatus of the firstembodiment. FIG. 3 is a schematic perspective view showing the externalappearance of the manual feed tray of the image processing apparatus ofthe first embodiment. FIG. 4 is a schematic perspective view showing themanual feed tray (first lowered position) of the image processingapparatus of the first embodiment.

As shown in FIG. 2 , the manual feed tray 12 has a flat plate shape as awhole. The manual feed tray 12 is rotatably supported by a rotarysupport shaft 37 provided on the device main body of the printer unit 3.FIG. 2 shows a state in which the manual feed tray 12 is open. Thedevice main body of the printer unit 3 is provided with a manual feedopen detection sensor 19 (not shown in FIG. 2 , see FIG. 11 ) thatdetects that the manual feed tray 12 is open. When the manual feed opendetection sensor 19 detects that the manual feed tray 12 is open, themanual feed open detection sensor 19 transmits a detection signal to acontrol circuit 60 described later.

Unless otherwise specified, the manual feed tray 12 in an open statewill be described below.

As shown in FIG. 3 , the manual feed tray 12 includes a main body 121,an upper plate 122, an elevating plate 13 (tray), and a biasing member14.

The main body 121 forms the bottom surface and the side surface of themanual feed tray 12.

The upper plate 122 and the elevating plate 13 are arranged in thisorder on the upper part of the main body 121 in the Xp direction. Theupper plate 122 and the elevating plate 13 form a placement surface onthe manual feed tray 12 on which the sheet S is placed. The elevatingplate 13 is an example of a tray on which a plurality of sheets arestacked.

In the main body 121, support units 123 that rotatably support theelevating plate 13 are provided on both side surfaces in the Ydirection. Each support unit 123 is arranged on the axis C1 extending inthe Y direction. Each support unit 123 is provided near the distal endof the upper plate 122 in the Xm direction.

The elevating plate 13 is rotatably engaged with each support unit 123.The elevating plate 13 is rotatable about the axis C1 in the ZX plane.

A flat distal end mounting surface 131 that is long in the Y directionis formed at the distal end of the elevating plate 13 in the Xmdirection. A distal end surface 132 extends downward at the end of thedistal end mounting surface 131 in the Xm direction.

A friction pad 133 that increases the frictional force against the sheetS is arranged at the center portion of the distal end mounting surface131 in the longitudinal direction. The friction pad 133 is provided at aposition where the friction pad can contact the pickup roller 112 whenviewed from the Zm direction. The friction pad 133 is made of a materialhaving a friction coefficient larger than that of the sheets S. Thefriction pad 133 prevents double feeding of the bottom sheet S placed onthe manual feed tray 12.

A cam contact surface 134 is formed outside the distal end mountingsurface 131 in the Y direction. However, in FIG. 3 , since theYm-direction cam contact surface 134 is not visible, only theYp-direction cam contact surface 134 is shown.

A cam plate unit 411 of a pressing member 41, which will be describedlater, contacts the cam contact surface 134. The shape of the camcontact surface 134 is not particularly limited as long as the elevatingplate 13 can be pushed down toward the main body 121 by the pressingforce from the cam plate unit 411 described later. In the example shownin FIG. 3 , each cam contact surface 134 is a flat surface along thedistal end mounting surface 131.

A biasing member 14 is arranged between the back side of the distal endmounting surface 131 and the bottom surface of the main body 121.

The configuration of the biasing member 14 is such that the elevatingplate 13 is pushed up in the direction in which the elevating plate 13is separated from the bottom surface portion of the main body 121. Forexample, as the biasing member 14, an appropriate spring or elasticmember may be used.

In the present embodiment, a compression coil spring is used as thebiasing member 14. The biasing members 14 are arranged below the distalend mounting surface 131 and near both ends in the Y direction.

The magnitude of the biasing force of the biasing member 14 is such thatthe uppermost sheet S abuts the pickup roller 112 and the frictionalforce capable of feeding the uppermost sheet S can be generated betweenthe uppermost sheet S and the pickup roller 112 when the stackablesheets S are set on the elevating plate 13.

With such a configuration, in the manual feed tray 12 alone, the distalend portion in the Xm direction of the elevating plate 13 biased by thebiasing member 14 protrudes above the main body 121. When an externalforce is applied to each cam contact surface 134 toward the bottomsurface portion of the main body 121, the elevating plate 13 descendstoward the bottom surface. At the lowermost position of the elevatingplate 13, the upper surface of the elevating plate 13 is flush with theupper plate 122.

The arrangement of the elevating plate 13 lowered to the lowest positionis called a first lowered position. FIG. 4 shows the manual feed tray 12in which the elevating plate 13 is moved to the first lowered position.

The arrangement in which the end of the elevating plate 13 in the Xmdirection is higher than the first lowered position with respect to themain body 121 is called a lifted position. In the manual feed tray 12alone shown in FIG. 3 , the maximum height of the elevating plate 13 ishigher than the height from the bottom surface portion of the main body121 to the pickup roller 112 in the state of being attached to theprinter unit 3. As shown in FIG. 2 , the lifted friction pad 133 comesinto contact with the pickup roller 112 in the state of being attachedto the printer unit 3. Therefore, the lifted position of the elevatingplate 13 is limited to the lower side of the position where the frictionpad 133 contacts the lower end of the pickup roller 112. Hereinafter,the position of the elevating plate 13 where the friction pad 133contacts the lower end of the pickup roller 112 is referred to as theuppermost position.

In the manual feed tray 12 in the opened state, the elevating plate 13is normally arranged at the first lowered position by the elevatingmechanism 40 described later. At this time, the user can place the sheetS on the elevating plate 13 and the upper plate 122 of the manual feedtray 12. For example, the sheet S can be placed up to a thicknesscorresponding to the distance from the friction pad 133 in the loweredposition to the lower end of the pickup roller 112.

The conveyance direction f of the sheet S in the manual feed unit 10 isa direction of advancing in the Xm direction along the upper surface ofthe elevating plate 13 on which the sheet S is placed.

As shown in FIG. 1 , the elevating mechanism 40 is provided in thedevice main body of the printer unit 3.

The elevating mechanism 40 switches the elevating plate 13 between thefirst lowered position and the lifted position in the manual feed tray12 in the opened state.

FIG. 5 is a schematic perspective view showing a configuration exampleof the elevating mechanism in the image processing apparatus of thefirst embodiment.

As shown in FIG. 5 , the elevating mechanism 40 includes the pressingmember 41, a drive motor 46, and a drive transmission unit 45.

The pressing member 41 abuts each cam contact surface 134 (see FIG. 7 ,not shown in FIG. 5 ) of the elevating plate 13 to regulate the heightof the elevating plate 13. The pressing member 41 is provided above eachcam contact surface 134.

Each pressing member 41 has a shape that is plane-symmetric to the ZXplane at the center of each arrangement position. Hereinafter, anexample of the pressing member 41 in the Ym direction will be described.Regarding the shape of the pressing member 41 in the Yp direction, theYp direction may be read as the Ym direction in the description of thepressing member 41 below.

The pressing member 41 includes a gear unit 417 and a cam plate unit411.

The gear unit 417 receives a driving force from the drive transmissionunit 45 described later. For example, the gear unit 417 is a spur gear.A rotation support shaft 44 is inserted in the center portion of thegear unit 417. In the center portion of the gear unit 417, a bearingthat allows the rotation support shaft 44 to be rotatably inserted isprovided. The gear unit 417 can rotate around the central axis O of therotation support shaft 44.

The cam plate unit 411 extends radially outward from the center portionof the gear unit 417 and has a distal end protruding radially outwardfrom the gear unit 417. An end surface of the cam plate unit 411 thatprotrudes radially outward of the gear unit 417 is a cam surface 412that presses the cam contact surface 134 downward.

The drive motor 46 is a motor that supplies a rotational driving forceto the drive transmission unit 45 described later by the rotation of amotor shaft 461. The drive motor 46 is fixed to the device main body onthe rear side of the printer unit 3 via a support member (not shown).

The drive motor 46 and the drive transmission unit 45 are used to swingthe pressing member 41. The drive motor 46 is communicatively connectedto the control circuit 60. For example, as the drive motor 46, a motorin which the motor shaft 461 rotates forward and backward is used.

The drive transmission unit 45 transmits the rotation of the motor shaft461 to the pressing member 41. In the example shown in FIG. 5 , thedrive transmission unit 45 is a gear transmission mechanism. In theexample shown in FIG. 5 , the motor shaft 461 extends in the Zdirection.

For example, the drive transmission unit 45 includes a first gear 451, asecond gear 452, a rotary shaft 43, a third gear 453, and a fourth gear454.

The first gear 451 is a worm gear fixed coaxially with the motor shaft461.

The second gear 452 is a worm wheel that meshes with the first gear 451.

The rotary shaft 43 is a rotary shaft that transmits the rotation of thesecond gear 452. The rotary shaft 43 is rotatably supported by bearings455 arranged on the front side plate and the rear side plate of thedevice main body of the printer unit 3.

The third gear 453 and the fourth gear 454 are provided at both ends ofthe rotary shaft 43. The third gear 453 and the fourth gear 454 transmitthe rotation of the rotary shaft 43 to the pressing members 41.

The fourth gear 454 is an idler gear provided in the transmission pathbetween the third gear 453 and the gear unit 417 of the pressing member41.

According to the drive transmission unit 45 having such a configuration,when the drive motor 46 rotates, the pressing members 41 rotate insynchronization with each other in the same direction. The pressingmember 41 swings around the central axis O according to the forward andreverse rotation of the drive motor 46.

FIG. 6 is a schematic diagram of a cross section showing the manual feedtray in the first lowered position of the elevating plate in the imageprocessing apparatus of the first embodiment. FIG. 7 is a schematicdiagram of a cross section showing the manual feed tray at the liftedposition of the elevating plate in the image processing apparatus of thefirst embodiment.

As shown in FIG. 6 , the cam plate unit 411 faces downward at the mostclockwise swing position. The cam plate unit 411 presses the cam contactsurface 134 downward. The elevating plate 13 is pushed down to the firstlowered position. The swing position is the home position of thepressing member 41. The presence of the pressing member 41 at the homeposition is detected by a home position detection sensor (not shown).

When the pressing member 41 rotates counterclockwise, the elevatingplate 13 ascends according to the shape of the cam surface 412.

As shown in FIG. 7 , the cam plate unit 411 faces upward at the mostcounterclockwise swing position. Since the cam plate unit 411 isseparated from the cam contact surface 134, the pressing force from thecam surface 412 is released. The elevating plate 13 is biased by thebiasing member 14 (not shown) to ascend to the uppermost position.

The elevating mechanism 40 can lift and lower the elevating plate 13between the first lowered position and the uppermost position byswinging the pressing member 41 by an appropriate angle.

As shown in FIG. 4 , in the device main body of the printer unit 3, aregulation plate 15 that regulates the position in the conveyancedirection of the sheet S (not shown) is arranged in the Xm directionfrom the manual feed unit 10.

FIG. 8 is a schematic diagram of a cross section showing an example ofthe manual feed unit in the image processing apparatus of the firstembodiment. FIG. 9 is a schematic diagram of the IX view in FIG. 8 .

As shown in FIG. 8 , the regulation plate 15 includes a first regulationsurface 151 and a second regulation surface 152.

The first regulation surface 151 is a flat surface that faces the distalend surface 132 of the elevating plate 13 and extends in a directionorthogonal to the upper surfaces of the elevating plate 13 and the upperplate 122 at the first lowered position. The first regulation surface151 extends from below the upper end of the elevating plate 13 at thefirst lowered position in the Xm direction to a position slightly lowerthan the upper end of the elevating plate 13 at the uppermost positionin the Xm direction.

The second regulation surface 152 is an inclined surface that extendsobliquely upward as advancing in the conveyance direction f from theupper end of the first regulation surface 151. The second regulationsurface 152 guides the lower surface of the sheet S conveyed from themanual feed unit 10 from below.

A resistance member 16 is provided on the first regulation surface 151.

The resistance member 16 abuts the leading ends St of the plurality ofsheets S in the conveyance direction f and imparts sliding resistance tothe leading ends of the plurality of sheets S that are lifted andlowered by the elevating mechanism 40. The sliding resistance applied tothe plurality of sheets S by the resistance member 16 is larger than thesliding resistance of the upper surface of the elevating plate 13 whichis the sheet stacking surface of the manual feed unit 10.

The method of fixing the resistance member 16 on the first regulationsurface 151 is not particularly limited. For example, the resistancemember 16 may be attached to the first regulation surface 151 via anadhesive or a pressure-sensitive adhesive.

The material used for the resistance member 16 is not particularlylimited as long as the sliding resistance is larger than that of theupper surface of the elevating plate 13. For example, since the uppersurface of the elevating plate 13 is made of a smooth metal surface, theresistance member 16 may have a non-smooth surface layer portion.

In the example schematically shown in FIG. 8 , the resistance member 16includes a napped material including a plurality of fibers extendingtoward the plurality of sheets S in the surface layer portion. Forexample, the resistance member 16 may be a napped cloth, a brush-shapedflocking member, or the like. When a plurality of sheets S come intocontact with such a napped material, fibers of the napped material enterbetween the sheets S. Therefore, when the plurality of sheets S move inthe stacking direction H with respect to the napped material, thesliding resistance increases.

The thickness t of the resistance member 16 is not particularly limitedas long as the required sliding resistance can be obtained.

More preferably, the surface layer portion of the resistance member 16that contacts the sheet S contains a material that does not easilycharge the sheet S. For example, more preferably, a part or the whole ofthe surface layer portion of the resistance member 16 is formed of aconductive material.

A suitable conductive material for the resistance member 16 is, forexample, aluminum.

The resistance member 16 may be provided on the entire surface of thefirst regulation surface 151 or may be provided on a part of the firstregulation surface 151.

When the resistance member 16 is provided on a part of the firstregulation surface 151, the arrangement position and the number of theresistance member 16 in the Y direction are not particularly limited aslong as the required sliding resistance can be imparted to the leadingends St of the sheets S of various sizes that can be conveyed from themanual feed unit 10.

In the example shown in FIG. 9 , one resistance member 16 is arranged ateach of four positions separated in the Y direction. Each resistancemember 16 has a strip shape extending in the stacking direction H of thesheets S. Each resistance member 16 has a length h and a width w(however, w<h) as viewed in the conveyance direction f. The lengths of hand w are not particularly limited as long as the required slidingresistance is obtained.

Since the printer unit 3 conveys the sheet S based on the center, thesheet S is placed on the sheet placing surface so that the center in thewidth direction is aligned with the conveyance center line Min themanual feed unit 10. Therefore, the resistance members 16 are arrangedin line symmetry to the conveyance center line M.

An actuator 17 is arranged in a groove 153 near the conveyance centerline M in the regulation plate 15.

FIG. 10 is a schematic diagram of a cross section taken along line X-Xin FIG. 9 .

As shown in FIG. 10 , the actuator 17 constitutes a sheet detectionmechanism that detects that the sheet S is placed, together with amanual feed sheet detection sensor 18.

The actuator 17 includes an actuator body 171 and a light blocking arm172.

The actuator body 171 is rotatably fixed to a rotation support shaft 173provided above the groove 153. The actuator body 171 can rotate in theZX plane about the rotation support shaft 173.

When no external force other than gravity is applied to the actuatorbody 171, a detection surface 174 formed by the side surface in the Xpdirection protrudes in the Xp direction more than the resistance member16 (see FIG. 8 ) on the first regulation surface 151. The protrusionamount to of the detection surface 174 from the first regulation surface151 is larger than the thickness t of the resistance member 16.

When the sheet S is placed on the manual feed tray 12, the leading endSt of the sheet S pushes the actuator body 171 in the Xm direction androtates the actuator body 171 clockwise in the drawing (see the chaindouble-dashed line). The protrusion amount tb of the detection surface174 from the first regulation surface 151 is t or less.

The light blocking arm 172 protrudes in an L shape from the side surfaceof the actuator body 171 in the Xm direction. The light blocking arm 172rotates in the same direction as the actuator body 171 in conjunctionwith the actuator body 171.

The manual feed sheet detection sensor 18 detects the presence of thesheet S on the manual feed tray 12 by detecting the rotational positionof the light blocking arm 172. For example, as the manual feed sheetdetection sensor 18, a photo interrupter in which a light emitting unitand a light receiving unit face each other is used. In the manual feedsheet detection sensor 18, when the height of the detection surface 174from the first regulation surface 151 is rotated to a position less thanthe thickness t of the resistance member 16, the light blocking arm isplaced in a position blocking the detection light of the photointerrupter.

The manual feed sheet detection sensor 18 is electrically connected tothe control circuit 60. The manual feed sheet detection sensor 18transmits a detection signal to the control circuit 60.

The control circuit 60 controls the entire image processing apparatus100 and each device part. For example, the control circuit 60 controlsthe control panel 1, the scanner unit 2, the printer unit 3, the sheetsupply unit 4, the conveyance unit 5, and the manual feed unit 10 toconvey the sheet S and form an image on the sheet S.

FIG. 11 is a block diagram of a control system in the image processingapparatus of the first embodiment.

As shown in FIG. 11 , the control circuit 60 is electrically connectedto the drive motor 46, the manual feed sheet detection sensor 18, andthe manual feed open detection sensor 19.

For example, the control circuit 60 transmits a control signal to thedrive motor 46 in the manual feed unit 10 to control the elevation ofthe elevation plate 13. The control circuit 60 lifts and lowers theelevating plate 13. When the elevating plate 13 is lifted and lowered,the leading end St of the sheet S slides on a lens frame 16, so that theplurality of sheets S placed on the manual feed tray 12 are separated.

For example, the control circuit 60 determines whether the manual feedtray 12 is open based on the detection signal from the manual opendetection sensor 19. The control circuit 60 determines whether the sheetS is placed on the manual feed tray 12 based on the detection signalfrom the manual feed sheet detection sensor 18.

As the device configuration of the control circuit 60, for example, aprocessor such as a central processing unit (CPU) may be used.

Next, the operation of the image processing apparatus 100 will bedescribed focusing on the separating operation on the manual feed tray12.

First, an outline of the print operation in the image processingapparatus 100 will be briefly described.

In the image processing apparatus 100 shown in FIG. 1 , conditions suchas the type of the sheet S to be image-formed and the number of printsare set based on the operation of the control panel 1 or an externalsignal. Image formation is started by the print start signal generatedthereafter. The image information is transmitted to the printer unit 3by reading the object to be copied by the scanner unit 2, or transmittedfrom the outside to the printer unit 3. The printer unit 3 supplies thesheet S in the sheet supply unit 4 or the sheet S in the manual feedunit 10 to the registration rollers 24 based on the control signalgenerated by the control circuit 60 in response to the condition settingand the reception of the print start signal. Hereinafter, as an example,a case where the sheet S is supplied from the manual feed unit 10 willbe described. The setting of the sheets S in the manual feed unit 10will be described later.

When the print start signal is received, the control circuit 60 controlsthe start of sheet feeding from the manual feed unit 10 and imageformation.

Each image forming unit 25 forms an electrostatic latent image on eachphotosensitive drum 7 based on the image information corresponding toeach color. Each electrostatic latent image is developed by thedeveloping device 8. Therefore, a toner image corresponding to theelectrostatic latent image is formed on the surface of eachphotosensitive drum 7.

Each toner image is primarily transferred onto the intermediate transferbelt 27 by each transfer roller. As the intermediate transfer belt 27moves, the toner images are sequentially superposed without causingcolor misregistration and are sent to the transfer unit 28.

The sheet S is fed from the registration rollers 24 to the transfer unit28. The toner image reaching the transfer unit 28 is secondarilytransferred to the sheet S. The toner image secondarily transferred isfixed to the sheet S by the fixing device 29. As a result, an image isformed on the sheet S.

Next, the operation of the manual feed unit 10 will be described indetail.

FIG. 12 is a flowchart of an image forming operation by manual sheetfeeding in the image processing apparatus of the first embodiment. FIGS.13A, 13B, and 13C are operation explanatory diagrams of the manual feedtray in the image processing apparatus of the first embodiment.

In the image processing apparatus 100, when an image is formed using thesheet S on the manual feed tray 12, the control circuit 60 performs thecontrol to execute ACT 1 to ACT 9 shown in FIG. 12 .

In ACT 1, the control circuit 60 determines whether the manual feed tray12 is open based on the detection signal from the manual feed opendetection sensor 19.

When a detection signal indicating that the manual feed tray 12 is inthe opened state is received from the manual feed open detection sensor19 (ACT 1: YES), the control circuit 60 executes ACT 2.

When the detection signal indicating that the manual feed tray 12 is inthe opened state is not received from the manual feed open detectionsensor 19 (ACT 1: NO), the control circuit 60 repeats ACT 1.

In ACT 2, the control circuit 60 transmits a control signal to theelevating mechanism 40 to lower the elevating plate 13 (described as“tray” in FIG. 12 ) to the first lowered position. The elevatingmechanism 40, which received the control signal from the control circuit60, drives the drive motor 46 to rotate the pressing members 41clockwise in the drawing as shown in FIG. 6 . The cam contact surface134 of the elevating plate 13 is pressed in the Zm direction by eachpressing member 41.

The drive motor 46 is driven until the pressing member 41 reaches thehome position. The elevating plate 13 rotates clockwise in the drawingaround the axis C1 and descends to the first lowered position.

Since the sheets S can be placed on the elevating plate 13 and the upperplate 122, the user places the required number of sheets S on theelevating plate 13 and the upper plate 122 of the manual feed tray 12.

When the sheet S is placed, as indicated by a chain double-dashed linein FIG. 10 , the actuator 17 pushed by the leading end St of the sheet Srotates in the clockwise direction in the drawing around the rotationsupport shaft 173. When the light blocking arm 172 moves to a positionthat shields light between the light emitting unit and the lightreceiving unit of the manual feed sheet detection sensor 18, the manualopen detection sensor 19 transmits the detection signal that detectsthat the sheet S is placed on the manual feed tray 12 to the controlcircuit 60.

In ACT 3, the control circuit 60 determines whether the sheet S isplaced on the manual feed tray 12 based on the detection signal of themanual feed sheet detection sensor 18.

When the detection signal is received from the manual feed sheetdetection sensor 18 (ACT 3: YES), the control circuit 60 executes ACT 4.

When the detection signal is not received from the manual feed sheetdetection sensor 18 (ACT 3: NO), the control circuit 60 repeats ACT 3.

In ACT 4, the control circuit 60 determines whether the print startsignal is received.

When the print start signal is received (ACT 4: YES), the controlcircuit 60 executes ACT 5.

When the print start signal is not received (ACT 4: NO), the controlcircuit 60 repeats ACT 3.

In ACT 5, the control circuit 60 transmits a control signal to theelevating mechanism 40 to execute the separation as follows.

The control circuit 60 transmits a control signal to the elevatingmechanism 40 to perform at least one elevating operation. In oneelevating operation, the elevating mechanism 40 lifts the elevatingplate 13 from the first lowered position to a predetermined liftedposition (see FIG. 13A) and lowers the elevating plate 13 from thelifted position to the first lowered position (see FIG. 13B).

As shown in FIG. 13A, the predetermined lifted position is a height atwhich the uppermost sheet S does not come into contact with the pickuproller 112 even when the maximum allowable stacking number of sheets Sare placed.

While the elevating plate 13 ascends, the leading end St of the sheet Sslides on the resistance member 16 and is pulled downward by the slidingresistance with the resistance member 16. When the fibers of theresistance member 16 enter between the sheets S in the first loweredposition, the lower sheet S is pressed by the fibers, so that a gap isgenerated between the upper sheet S and the lower sheet S. The fibersslipped from between the sheets enter between the sheets S in the lowerlayer.

As such, the leading ends St of the plurality of sheets S in contactwith the resistance member 16 are separated from the upper side to thelower side while the elevating plate 13 is ascending. In the pluralityof separated sheets S, since air enters between the sheets in thevicinity of the leading end St, the adhesion force between the sheets Sthat are in close contact with each other is reduced in the vicinity ofthe leading ends St.

As shown in FIG. 13B, while the elevating plate 13 descends toward thefirst lowered position, the leading end St of the sheet S slides on theresistance member 16 and is rolled up by the sliding resistance with theresistance member 16. When the fibers of the resistance member 16 enterbetween the sheets Sat the lifted position, the upper sheet S is pressedby the fibers, so that a gap is formed between the upper sheet S and thelower sheet S. The fibers slipped from between the sheets enter betweenthe sheets S in the upper layers.

As such, the leading ends St of the plurality of sheets S in contactwith the resistance member 16 are separated from the lower side to theupper side while the elevating plate 13 is descending. In the pluralityof separated sheets S, since air enters between the sheets in thevicinity of the leading end St, the adhesion force between the sheets Sthat are in close contact with each other is reduced in the vicinity ofthe leading ends St.

In particular, when the elevating plate 13 is ascending, the sheets Sare repeatedly rolled up by sliding on the resistance member 16 and thendropped downward by gravity. Therefore, the plurality of sheets S aremore strongly separated when descending, together with the fact that theplurality of sheets S are separated to some extent when ascending.

When the separation is performed in such manner, frictional charging mayoccur on the resistance member 16 and the leading end S of the sheet S.If the charge amount of the sheet S is too large, the conveyance may behindered.

If the material of the resistance member 16 contains a conductivematerial, the charge of the sheet S is removed, and thus the chargeamount of the sheet S can be reduced.

When the elevating operation of the elevating plate 13 is performed apredetermined number of times, ACT 5 ends. After that, the controlcircuit 60 executes ACT 6.

In ACT 6, the control circuit 60 transmits a control signal to theelevating mechanism 40 to move the elevating plate 13 from the firstlowered position to the uppermost position.

The control circuit 60 transmits a control signal to the elevatingmechanism 40 to rotate the pressing member 41 to a position where thecam surface 412 is separated from the cam contact surface 134 (see FIG.7 ).

The elevating plate 13 is released from the pressing force of thepressing member 41 and is biased upward by the biasing member 14. Theelevating plate 13 is lifted to the uppermost position where theuppermost surface of the plurality of sheets S are in contact with thepickup roller 112.

Thus, ACT 6 is completed. After that, the control circuit 60 executesACT 7.

In ACT 7, the control circuit 60 transmits a control signal to eachdevice part of the image processing apparatus 100 to convey one sheet Sfrom the manual feed tray 12 to the conveyance unit 5 and perform theabove-described printing operation.

In the present embodiment, the separation is performed in ACT 5. Asshown in FIG. 13C, when the pickup roller 112 feeds the sheet S from themanual feed tray 12, it is possible to prevent the double feeding ofthree or more sheets S. Even if two sheets S are double-fed, since themanual sheet feed unit 11 includes the separation roller 113, theuppermost one sheet S among the double-fed sheets can be conveyed to theconveyance unit 5.

Thus, ACT 7 is completed. After that, the control circuit 60 executesACT 8. There may be a gap between adjacent sheets.

In ACT 8, the control circuit 60 transmits a control signal to theelevating mechanism 40 to lower the elevating plate 13 from theuppermost position to the first lowered position.

The control circuit 60 transmits a control signal to the elevatingmechanism 40 to move the pressing member 41 to the home position.

The elevating plate 13 moves to the first lowered position, and thus,the user can place the sheet S on the manual feed tray 12 as necessary.

Thus, the image forming operation when the sheet S is fed from themanual feed tray 12 is completed.

According to the image processing apparatus 100 of the presentembodiment, since the manual feed unit 10 includes the resistance member16 and the control circuit 60 that lifts and lowers the elevating plate13 to perform the separation, it is possible to prevent double feedingin the manual feed unit 10 even if the user does not separate the sheetsS before placing the sheets S.

Second Embodiment

A sheet conveying device and an image processing apparatus according toa second embodiment will be described.

As shown in FIG. 1 , an image processing apparatus 101 of the presentembodiment includes a sheet supply unit 70 (sheet conveying device) anda control circuit 61 instead of the sheet supply unit 4 and the controlcircuit 60 of the first embodiment.

The following description will focus on the points that differ from thefirst embodiment.

FIG. 14 is a schematic diagram of a cross section of the sheet conveyingdevice of the second embodiment. FIG. 15 is a schematic perspective viewof the sheet conveying device according to the second embodiment.

As shown in FIG. 14 , the sheet supply unit 70 is the same as the sheetsupply unit 4 except that the resistance member 16 is added to the sheetfeed cassette 20 of the sheet supply unit 4 in the first embodiment.That is, the sheet supply unit 70 includes, as in the first embodiment,the same cassette sheet feed unit 21 and sheet feed cassette 20, anelevating mechanism 73, and a tray-up detection mechanism 72 (see FIG.15 ). However, the description of the elevating mechanism 73 and thetray-up detection mechanism 72 is omitted in the first embodiment.Hereinafter, the points omitted in the first embodiment will bedescribed.

The sheet feed cassette 20 is a box type that opens in the Zp directionas a whole. In the sheet feed cassette 20, the Xp direction is the sheetS conveyance direction. Each sheet feed cassette 20 can be pulled out inthe Yp direction, as in the case of the image processing apparatus 100.Unless otherwise specified, an example in which the sheet feed cassette20 is mounted inside the image processing apparatus 101 will bedescribed.

The sheet feed cassette 20 has a bottom surface portion 201 and aplurality of walls extending in the Zp direction from the outer edge ofthe bottom surface portion 201.

The bottom surface portion 201 supports the sheet S accommodated in thesheet feed cassette 20 from below.

As shown in FIGS. 14 and 15 , the plurality of walls include a front endwall 203 (regulation plate), a front side wall 204 (see FIG. 15 ), arear side wall 205, and a rear end wall 206 (see FIG. 14 ).

The front end wall 203 provided in the Xp direction is an example of aregulation plate that regulates the position of the leading end of thesheet S in the conveyance direction.

At the upper end of the front end wall 203, a conveyance guide plate2031 that guides the conveyance of the sheet S from below extendsobliquely upward toward the nip between the sheet feed roller 211 andthe separation roller 213.

The resistance member 16 similar to the regulation plate 15 in the firstembodiment is provided on the surface of the front end wall 203 in theXm direction. In the present embodiment, as shown in FIG. 15 , thearrangement is the same as that of the first embodiment, except that theresistance members 16 are provided at six positions separated in the Ydirection. Each of the resistance members 16 linearly extends in the Zdirection from the bottom surface portion 201 to the upper end of thefront end wall 203.

In the Yp direction and the Ym direction, the front side wall 204 andthe rear side wall 205 are provided with a space wider than the maximumwidth of the sheet S that can be stored in the sheet feed cassette 20.

A front cover 2041 covers the surface of the front side wall 204 in theYp direction. In the center portion of the front cover 2041 in the Xdirection, a pull-out operation unit 2042 for pulling out the sheet feedcassette 20 is provided.

For example, the pull-out operation unit 2042 includes a lever that canbe operated by being held by the user. When the user holds the lever ofthe pull-out operation unit 2042, the locked state of the sheet feedcassette 20 with respect to the device main body is released. The sheetfeed cassette 20 can be pulled out in the Yp direction.

In the Xm direction, the rear end wall 206 connected to the ends of thefront side wall 204 and the rear side wall 205 in the Xm direction isprovided. The distance between the rear end wall 206 and the front endwall 203 in the X direction is wider than the maximum length of thesheet S that can be stored in the sheet feed cassette 20.

The sheet feed cassette 20 further includes an elevating plate 202(tray), a side fence 207, and an end fence 208. The elevating plate 202is an example of a tray on which a plurality of sheets are stacked.

The elevating plate 202 supports the leading end side of the sheet Splaced on the bottom surface portion 201 in the conveyance directionfrom below.

The elevating plate 202 includes a sheet mounting plate 2021, sideplates 2022, and a pivotal connection unit 2023.

The sheet mounting plate 2021 is a smooth metal plate having low slidingfriction with the surface of the sheet S. As shown in FIG. 15 , sidefences 207 that sandwich both ends in the width direction of the sheet Spenetrate through the sheet mounting plate 2021 in the thicknessdirection.

Similar to the elevating plate 13, a friction pad 133 is arranged at theend in the Xp direction at the center of the sheet mounting plate 2021in the Y direction.

The side plates 2022 respectively protrude in the Zp direction from theends of the sheet mounting plate 2021 in the Y direction. Each sideplate 2022 is parallel to the ZX plane.

The pivotal connection unit 2023 rotatably connects the side plates 2022to the front side wall 204 and the rear side wall 205.

For example, FIG. 14 shows the pivotal connection unit 2023 which isconnected to the rear side wall 205. The pivotal connection unit 2023 isprovided on the upper end of the side plate 2022.

The pivotal connection unit 2023 is configured by a shaft or a holeprovided on the side plate 2022.

For example, when the pivotal connection unit 2023 is an axis, thepivotal connection unit 2023 extends in the Y direction from each sideplate 2022 toward the rear side wall 205 and the front side wall 204.The rear side wall 205 and the front side wall 204 are formed with holesinto which the pivotal connection unit 2023 is rotatably fitted.

For example, when the pivotal connection unit 2023 is a hole,protrusions extending from the rear side wall 205 and the front sidewall 204 in the Y direction are provided. The pivotal connection unit2023 is rotatably fitted to the protrusion.

Each pivotal connection unit 2023 is formed coaxially with the axis C2extending in the Y direction.

The elevating plate 202 is connected to the rear side wall 205 and thefront side wall 204 via the pivotal connection unit 2023 to be rotatablearound the axis C2.

The end fence 208 regulates the position of the sheet S placed in thesheet feed cassette 20 in the Xm direction. The end fence 208 is fixedon the bottom surface portion 201 to be able to be relocated dependingon the length of the sheet S.

FIG. 16 is a schematic perspective view of an elevating mechanism in theimage processing apparatus of the second embodiment. FIG. 17 is a blockdiagram of a control system in the image processing apparatus of thesecond embodiment. FIG. 18 is an operation explanatory diagram of thetray detection sensor in the image processing apparatus of the secondembodiment.

As shown in FIG. 16 , the elevating mechanism. 73 includes a tray-upshaft 731, a pressing plate 732, a connection unit 735, an actuator 733,a light blocking plate 734, and a drive unit 75.

The tray-up shaft 731 is a shaft member extending in the Y direction. Asshown in FIG. 14 , the tray-up shaft 731 is arranged below the sheetmounting plate 2021. The tray-up shaft 731 extends from the position ofthe sheet feed cassette 20 protruding from the rear side wall 205 in theYm direction to the center portion of the sheet feed cassette 20 in theY direction.

The tray-up shaft 731 is supported by the sheet feed cassette 20 to berotatable about the central axis thereof.

As shown in FIG. 16 , the pressing plate 732 is provided at the end ofthe tray-up shaft 731 in the Yp direction, and the connection unit 735is provided at the end in the Ym direction.

The pressing plate 732 is fixed to the end of the tray-up shaft 731 inthe Yp direction. The pressing plate 732 extends in the radial directionof the tray-up shaft 731.

As shown in FIG. 14 , when the upper surface of the sheet mounting plate2021 is flush with the upper surface of the bottom surface portion 201,the pressing plate 732 is arranged between the sheet mounting plate 2021and the bottom surface of the sheet feed cassette 20.

When the tray-up shaft 731 is rotated counterclockwise when viewed fromthe Ym direction, the pressing plate 732 rotates together with thetray-up shaft 731 and gradually stands up toward the sheet mountingplate 2021.

As shown in FIG. 16 , the connection unit 735 is fixed to the end of thetray-up shaft 731 in the Ym direction. The connection unit 735 isdetachably connected to a coupling 752 of the drive unit 75 describedlater in the Y direction. The connection unit 735 engages with thecoupling 752 around the central axis of the tray-up shaft 731.

The engagement structure between the connection unit 735 and thecoupling 752 is not particularly limited. For example, if the coupling752 has a cylindrical shape in which an engaging groove that opens inthe Yp direction is provided in the circumferential direction, theconnection unit 735 may include an engaging shaft that can be insertedinto the engaging groove from the Ym direction and protrudes radiallyoutward.

The actuator 733 is a protruding piece that extends from the outerperipheral portion of the connection unit 735 to the radial outside ofthe tray-up shaft 731.

The protruding direction of the actuator 733 is approximately 90 degreescounterclockwise with respect to the pressing plate 732 when viewed fromthe Ym direction. When the pressing plate 732 extends substantiallyhorizontally in the ZX plane, the actuator 733 protrudes verticallyupward.

The light blocking plate 734 protrudes in the Ym direction from thedistal end portion of the actuator 733 in the protruding direction.

As shown in FIG. 15 , the drive unit 75 is fixed to the device main bodyof the sheet supply unit 70 in the Ym direction from the rear side wall205 of the sheet feed cassette 20.

As shown in FIG. 16 , the drive unit 75 includes the coupling 752, atray-up motor 753, and a tray detection sensor 751.

The coupling 752 can be attached to and detached from the connectionunit 735 in the Y direction and can be engaged with the connection unit735 in the circumferential direction of the tray-up shaft 731 whenconnecting to the connection unit 735.

The tray-up motor 753 includes a motor shaft extending in the Ydirection. The coupling 752 is fixed to the end of the motor shaft inthe Yp direction.

As shown in FIG. 17 , the tray-up motor 753 is communicatively connectedto the control circuit 61 described later. The rotation amount androtation direction of the motor shaft of the tray-up motor 753 arecontrolled according to the control signal transmitted from the controlcircuit 61.

The tray detection sensor 751 is electrically connected to the controlcircuit 61 described later. The tray detection sensor 751 detectswhether the sheet mounting plate 2021 started to ascend, and transmits adetection signal to the control circuit 61 when the sheet mounting plate2021 starts to ascend.

In the present embodiment, the tray detection sensor 751 is configuredof a photo interrupter. The tray detection sensor 751 is arranged on themoving path of the light blocking plate 734 on the surface of the driveunit 75 in the Yp direction.

As shown in FIG. 18 , the tray detection sensor 751 includes a lightemitting unit and a light receiving unit for the detection light, and adetection area D for emitting the detection light is formed between thelight emitting unit and the light receiving unit.

When the pressing plate 732 is not pressing the sheet mounting plate2021, the actuator 733 is at the position of the actuator 7331 shown bythe chain double-dashed line. Here, the light blocking plate 734 of theactuator 7331 is located outside the detection area D.

When the pressing plate 732 starts pressing the sheet mounting plate2021, the actuator 733 is rotating to the position of the actuator 7332shown by the solid line. Here, the light blocking plate 734 of theactuator 7332 blocks the detection light in the detection area D. Thetray detection sensor 751 transmits a detection signal to the controlcircuit 61 when the control circuit 61 detects that the sheet mountingplate 2021 started to ascend.

As will be described later, the detection signal of the tray detectionsensor 751 is used to control the amount of elevation of the sheetmounting plate 2021 in the elevation mechanism 73.

As shown in FIG. 15 , the tray-up detection mechanism 72 includes anactuator 721 and a tray-up sensor 722.

The tray-up detection mechanism 72 is fixed to the side surface in theXm direction of a stay 213 extending in the Y direction in the cassettesheet feed unit 21 of the printer unit 3.

The tray-up detection mechanism 72 detects that the leading end of thesheet S placed on the sheet feed cassette 20 in the conveyance directionascended to a position to be in contact with the pickup roller 212.

The actuator 721 is a lever rotatably supported by a rotation supportshaft 215 extending from the stay 215 in the Xm direction. The actuator721 is rotatable in the YZ plane.

The actuator 721 includes a detection unit 724 that abuts on theuppermost surface of the sheets S in the sheet feed cassette 20 anddetects the position of the uppermost surface. When the detection unit724 is not in contact with the sheet S, the actuator 721 is inclineddownward due to its own weight. When the detection unit 724 is pushed upto the maximum by the sheets S, the actuator 721 becomes substantiallyhorizontal.

The detection unit 724 is pushed up to the maximum when the uppermostsurface of the sheets S stored in the sheet feed cassette 20 is liftedto a position to be in contact with the pickup roller 212 from below.

When the sheet mounting plate 2021 is lifted without the sheet S beingplaced on the sheet mounting plate 2021, the detection unit 724 isdepressed in the hole formed in the sheet mounting plate 2021. Here, thedetection unit 724 is not pushed up to the maximum.

The tray-up sensor 722 detects that the detection unit 724 was pushed upto the maximum. For example, a photo interrupter is used as the tray-upsensor 722.

As shown in FIG. 17 , the tray-up sensor 722 is communicativelyconnected to a control circuit 61 described later. When the tray-upsensor 722 detects that the detection unit 724 was pushed up to themaximum, the tray-up sensor 722 transmits a detection signal to thecontrol circuit 61.

The control circuit 61 is the same as the control circuit 60 in thefirst embodiment, except that the sheet supply unit 70 performs theseparating operation of the sheets S placed on the sheet feed cassette20.

As shown in FIG. 17 , the control circuit 61 is electrically connectedto the tray-up motor 753, the tray detection sensor 751, and the tray-upsensor 722.

For example, the control circuit 61 transmits a control signal to thedrive unit 75 in the elevating mechanism 73 to control the elevation ofthe sheet mounting plate 2021. The control circuit 61 lifts and lowersthe sheet mounting plate 2021 to separate the plurality of sheets Splaced on the sheet feed cassette 20.

Next, the operation of the sheet supply unit 70 in the image processingapparatus 101 will be described focusing on the separating operation ofthe sheet feed cassette 20. Descriptions of operations common to thefirst embodiment may be omitted.

FIG. 19 is a flowchart of an image forming operation by cassette sheetfeeding in the image processing apparatus of the second embodiment.FIGS. 20A and 20B are operation explanatory diagrams of the sheetconveying device of the second embodiment.

In the image processing apparatus 101, when an image is formed using thesheet S in the sheet feed cassette 20, the control circuit 61 performsthe control to execute ACT 11 to ACT 16 shown in FIG. 19 .

In the following, an example in which a plurality of sheets S are placedin the sheet feed cassette 20 in advance will be described. As shown inFIG. 14 , the pressing plate 732 extends substantially horizontally, andthe elevating plate 202 is not pressed by the pressing plate 732. Here,the upper surface of the sheet mounting plate 2021 is flush with theupper surface of the bottom surface portion 201. Such a position of thesheet mounting plate 2021 is the lowermost position in the sheet feedcassette 20. The arrangement of the elevating plate 202 in which thesheet mounting plate 2021 is lowered to the lowermost position isreferred to as a first lowered position.

The uppermost surface of the sheets S is separated below the pickuproller 212.

The leading end St of each sheet S in the conveyance direction is incontact with the resistance member 16.

In ACT 11, it is determined whether the control circuit 61 received theprint start signal.

When the print start signal is received (ACT 11: YES), the controlcircuit 61 executes ACT 12.

When the print start signal is not received (ACT 11: NO), the controlcircuit 61 repeats ACT 11.

In ACT 12, the control circuit 61 transmits a control signal to theelevating mechanism 73 to execute the separation as follows.

The control circuit 61 transmits a control signal to the elevatingmechanism 73 to perform at least one elevating operation. In oneelevating operation, the elevating mechanism 73 lifts the sheet mountingplate 2021 from the first lowered position to a predetermined liftedposition (see FIG. 20A) and lowers the sheet mounting plate 2021 fromthe lifted position to the first lowered position (see FIG. 14 ), andtransmits a control signal for performing the elevating operation.

As shown in FIG. 20A, the elevating mechanism 73 that received thecontrol signal drives the tray-up motor 753 to rotate the tray-up shaft731 counterclockwise when viewed from the Ym direction.

As shown in FIG. 18 , when the actuator 733 rotates to the position ofthe actuator 7332, the tray detection sensor 751 transmits a detectionsignal to the control circuit 61.

The control circuit 61 further rotates the tray-up shaft 731counterclockwise until the predetermined ascending time elapses from thetime when the detection signal is received. Along with the tray-up shaft731, the pressing plate 732 also rotates counterclockwise. The elevatingplate 202 pressed from below by the pressing plate 732 rotatescounterclockwise about the axis C2.

The ascending time is the time required for the elevating plate 202 toreach the lifted position in the separating operation. As shown in FIG.20A, the predetermined lifted position in the separating operation is ata height at which the uppermost sheet S does not come into contact withthe pickup roller 212 even if the maximum allowable stacking number ofsheets S are placed.

The leading end St of the sheet S slides on the resistance member 16while the elevating plate 202 is ascending. Here, the resistance member16 has the same action as when the elevating plate 13 in the firstembodiment ascends. As a result, the leading ends St of the plurality ofsheets S in contact with the resistance member 16 are separated from theupper side to the lower side while the elevating plate 202 is ascending.In the plurality of separated sheets S, since air enters between thesheets in the vicinity of the leading end St, the adhesion force betweenthe sheets S that are in close contact with each other is reduced in thevicinity of the leading ends St.

When the ascending time passed, the control circuit 61 switches therotation direction of the tray-up motor 753 to lower the elevating plate202.

As shown in FIG. 20B, while the elevating plate 202 descends toward thefirst lowered position, the leading end St of the sheet S slides on theresistance member 16 and is rolled up. Here, the resistance member 16has the same action as when the elevating plate 13 in the firstembodiment descends. As a result, the leading ends St of the pluralityof sheets S in contact with the resistance member 16 are separated fromthe lower side to the upper side while the elevating plate 202 isdescending. In the plurality of separated sheets S, since air entersbetween the sheets in the vicinity of the leading end St, the adhesionforce between the sheets S that are in close contact with each other isreduced in the vicinity of the leading end St.

In particular, when the elevating plate 13 is lowered, the sheets S arerepeatedly rolled up by sliding on the resistance member 16 and thendropped downward by gravity. Therefore, the plurality of sheets S aremore strongly separated when descending, together with the fact that theplurality of sheets S are separated to some extent when ascending.

When the elevating operation of the elevating plate 202 is performed apredetermined number of times, ACT 12 ends. After that, the controlcircuit 61 executes ACT 13.

In ACT 13, the control circuit 61 transmits a control signal to theelevating mechanism 73 to move the elevating plate 202 from the firstlowered position to the uppermost position.

The control circuit 61 lifts the elevating plate 202 by the elevatingmechanism 73, similarly to ACT 12.

As the elevating plate 202 ascends, the uppermost surface of the sheetsS pushes up the detection unit 724 of the actuator 721. When theelevating plate 202 reaches the uppermost position, the tray-up sensor722 detects the actuator 721 pushed up to the uppermost surface of thesheets S and transmits a detection signal to the control circuit 61.

Upon receiving the detection signal from the tray-up sensor 722, thecontrol circuit 61 transmits a control signal for stopping the tray-upmotor 753 to the drive unit 75.

As such, the elevating plate 202 ascends to the uppermost position wherethe uppermost surface of the plurality of sheets S is in contact withthe pickup roller 112.

Thus, ACT 13 is completed. After that, the control circuit 61 executesACT 14.

However, when the sheet S is not placed on the elevating plate 202, adetection signal is not transmitted from the tray-up sensor 722 to thecontrol circuit 61 even if the time for the elevating plate 202 toascend to the uppermost position elapses. Here, the control circuit 61determines that the sheet S is not placed.

Here, the control circuit 61 may display on the control panel 1 that thesheet S is not placed in the sheet cassette 20 after the elevating plate202 is lowered to the first lowered position. The user pulls out thesheet feed cassette 20, replenishes the sheets S, and pushes the sheetfeed cassette 20 into the sheet supply unit 70. When the control circuit61 detects that the sheet feed cassette 20 is mounted, the controlcircuit 61 executes ACT 12.

However, the control circuit 61 may display on the control panel 1 thatthe sheet S is not placed in the sheet cassette 20 while the elevatingplate 202 is kept at the uppermost position. Here, when the user pullsthe sheet feed cassette 20, the engagement between the coupling 752 andthe connection unit 735 is released, and thus the elevating plate 202descends to the first lowered position by its own weight. The user canpull out the sheet feed cassette 20. After that, the user replenishesthe sheets S and pushes the sheet feed cassette 20 into the sheet supplyunit 70, as described above. When the control circuit 61 detects thatthe sheet feed cassette 20 is mounted, the control circuit 61 executesACT 12.

ACTS 14 and 15 are the same as ACTS 7 and 8 in the first embodiment,except that one sheet S is conveyed from the sheet feed cassette 20 tothe conveyance unit 5.

In ACT 16, the control circuit 61 transmits a control signal to theelevating mechanism 73 to lower the elevating plate 202 from theuppermost position to the first lowered position.

Thus, the image forming operation when the sheet S is fed from the sheetfeed cassette 20 is completed.

According to the image processing apparatus 101 of the presentembodiment, since the sheet feed cassette 20 includes the resistancemember 16 and the control circuit 61 that lifts and lowers the elevatingplate 202 to perform the separation, it is possible to prevent doublefeeding in the sheet supply unit 70 even if the user does not separatethe sheets S before placing the sheets S.

Third Embodiment

A sheet conveying device and an image processing apparatus according toa third embodiment will be described.

As shown in FIG. 1 , an image processing apparatus 102 of the presentembodiment includes a sheet supply unit 80 (sheet conveying device) anda control circuit 62 instead of the sheet supply unit 70 and the controlcircuit 61 of the second embodiment.

The following description focuses on the points that differ from thesecond embodiment.

FIG. 21 is a schematic diagram of a cross section of the sheet conveyingdevice (first lowered position) of the third embodiment. FIG. 22 is ablock diagram of a control system in the image processing apparatus ofthe third embodiment. FIG. 23 is a schematic diagram of a cross sectionof the sheet conveying device (second lowered position) of the thirdembodiment.

As shown in FIG. 21 , the sheet supply unit 80 includes a sheet feedcassette 81 instead of the sheet feed cassette 20 of the sheet supplyunit 70 in the second embodiment. The sheet supply unit 80 furtherincludes a pressing member 82 and a pressing member elevating mechanism83.

The sheet feed cassette 81 differs from the sheet feed cassette 20 inthe second embodiment in that an inclined bottom surface portion 811 isprovided below the sheet mounting plate 2021. In the example shown inFIG. 21 , the conveyance guide plate 2031 in the sheet feed cassette 20is deleted. However, the conveyance guide plate 2031 may also beprovided on the front end wall 203 of the sheet feed cassette 81.

The inclined bottom surface portion 811 is inclined in the Zm directionfrom the end of the bottom surface portion 201 close to the end of thesheet mounting plate 2021 in the first lowered position in the Xmdirection as advancing in the Xp direction.

A lower space R in which the sheet mounting plate 2021 can rotate isformed between the sheet mounting plate 2021 and the inclined bottomsurface portion 811 in the first lowered position.

The pressing member 82 presses the sheet S above the bottom surfaceportion 201 from above. The pressing member 82 is arranged above the endof the bottom surface portion 201 in the Xp direction.

The pressing member 82 is arranged in a range in which the uppermostsurface of the sheets S having the smallest width that can be set in thesheet feed cassette 81 can be pressed in the Y direction.

The pressing member 82 is supported by a pressing member elevatingmechanism 83 fixed to the device main body of the sheet supply unit 80to be able to be lifted and lowered in the Z direction.

The pressing member elevating mechanism 83 includes, for example, adriving member such as a motor or a solenoid. As shown in FIG. 22 , thepressing member elevating mechanism 83 is communicatively connected tothe control circuit 62. The pressing member elevating mechanism 83 liftsand lowers the pressing member 82 based on the control signaltransmitted from the control circuit 62.

According to the present embodiment, as shown in FIG. 23 , when viewedfrom the Ym direction, the sheet mounting plate 2021 is rotatedclockwise about the axis C2, so that the sheet mounting plate 2021 canbe lowered inside the lower space R lower than the upper surface of thebottom surface portion 201. As shown in FIG. 23 , the position of theelevating plate 202 where the sheet mounting plate 2021 is lowered tothe lowermost side is referred to as a second lowered position.

When the sheet S is placed on the sheet mounting plate 2021 and thesheet mounting plate 2021 is rotated below the first lowered position,the sheet S can be bent at the end of the sheet mounting plate 2021 inthe Xm direction.

The pressing member 82 can press the sheet S at a position close to thebent portion of the sheet S.

The lower end of the front end wall 203 in the present embodiment isconnected to the end of the inclined bottom surface portion 811 in theXp direction. The resistance member 16 provided on the front end wall203 in the present embodiment extends to a position that is equal to orlower than the height of the end in the Xp direction of the sheetmounting plate 2021 in the second lowered position. Therefore, theresistance member 16 can come into contact with the leading end St ofthe sheet S placed on the sheet mounting plate 2021 in the secondlowered position.

As shown in FIG. 22 , the control circuit 62 is electrically connectedto the tray-up motor 753, the tray detection sensor 751, the tray-upsensor 722, and the pressing member elevating mechanism 83.

The control circuit 62 is similar to that of the second embodiment,except that the control circuit 62 can control the elevating mechanism73 to lift and lower the elevating plate 202 between the second loweredposition and the uppermost position.

Next, the operation of the sheet supply unit 80 in the image processingapparatus 102 will be described focusing on the separating operation ofthe sheet feed cassette 81. Descriptions of operations common to thesecond embodiment may be omitted.

FIG. 24 is a flowchart of an image forming operation by cassette sheetfeeding in the image processing apparatus of the third embodiment.

In the image processing apparatus 102, when an image is formed using thesheet S in the sheet feed cassette 81, the control circuit 62 performsthe control to execute ACT 21 to ACT 28 shown in FIG. 24 .

In the following, an example in which a plurality of sheets S are placedin the sheet feed cassette 81 in advance will be described. As shown inFIG. 21 , the pressing plate 732 supports the sheet mounting plate 2021from below so that the sheet mounting plate 2021 is flush with the uppersurface of the bottom surface portion 201. Such a position of the sheetmounting plate 2021 is the first lowered position in this embodiment.

The pressing member 82 is separated upward from the uppermost surface ofthe sheets S.

The leading end St of each sheet S in the conveyance direction is incontact with the resistance member 16.

In ACT 21, the control circuit 62 determines whether the print startsignal is received.

When the print start signal is received (ACT 21: YES), the controlcircuit 62 executes ACT 22.

When the print start signal is not received (ACT 21: NO), the controlcircuit 62 repeats ACT 21.

In ACT 22, the control circuit 62 transmits a control signal to lowerthe pressing member 82 to the position to press the uppermost surface ofthe sheets S to the pressing member elevating mechanism 83.

As shown in the dash-dotted line in FIG. 21 , the pressing member 82presses the uppermost surface of the sheets S toward the bottom surfaceportion 201.

After ACT 22, ACT 23 is executed.

In ACT 23, the control circuit 62 transmits a control signal to theelevating mechanism 73 to execute the separation as follows.

The control circuit 62 transmits a control signal to the elevatingmechanism 73 to perform at least one elevating operation.

In one elevating operation, the elevating mechanism 73 lifts the sheetmounting plate 2021 from the first lowered position to a predeterminedlifted position.

In the present embodiment, the predetermined lifted position is theuppermost position where the uppermost surface of the sheets S contactsthe pickup roller 212, or the lifted position near the uppermostposition.

In the example shown in FIG. 21 , the maximum allowable number of sheetsS are placed, and the uppermost surface of the sheets S is in contactwith the pickup roller 212 when the sheet feed cassette 81 is mounted tothe sheet supply unit 80. Here, the elevating mechanism 73 does not liftthe elevating plate 202.

After the elevating plate 202 reaches the predetermined lifted position,the elevating mechanism 73 of the present embodiment lowers theelevating plate 202 to the second lowered position.

In the present embodiment, when the above-described elevating operationis performed, the leading ends St of the sheets S are separated as inthe second embodiment, except that the elevating range is different.

In the present embodiment, the ascending operation may not be performeddepending on the stacking amount of the sheets S. However, as describedin the second embodiment, the degree to which the sheet S is separatedis stronger when the sheet S is lowered than when the sheet S is lifted.Therefore, in the present embodiment as well, the same action as that ofthe second embodiment can be obtained by the separation.

In the present embodiment, the sheet S is pressed from above by thepressing member 82 toward the bottom surface portion 201 during theseparation. Therefore, it is possible to prevent the sheet S fromslipping and pressing the resistance member 16 too much when the sheet Sdescends. As a result, it is possible to prevent the sliding resistancebetween the resistance member 16 and the leading end St of the sheet Sfrom increasing excessively when ascending.

If the sliding resistance between the resistance member 16 and theleading end St becomes too large, the size of the tray-up motor 753 maybecome large, or the leading end St of the sheet S may be damaged duringsliding. In the present embodiment, such a possibility can be prevented.

However, when the stacking capacity of the sheet feed cassette 81 is notso large, the sliding resistance may not be excessive even if the sheetS is not pressed by the pressing member 82. Here, the pressing member 82and the pressing member elevating mechanism 83 may be omitted.

In the case of omitting the pressing member 82 and the pressing memberelevating mechanism. 83, since the stack of the stacked sheets S is bentdownward due to its own weight when the elevating plate 202 descends,shear slip occurs between the sheets S. When shear slip occurs, theadhesion between the sheets S is relaxed, and the separating effect isincreased.

When the elevating operation of the elevating plate 202 is performed apredetermined number of times, ACT 23 ends. After that, the controlcircuit 61 executes ACT 24.

In ACT 24, the control circuit 62 transmits a control signal to thepressing member elevating mechanism 83 to lift the pressing member 82from the uppermost surface of the sheets S to a position where thepressing member 82 is separated upward.

As a result, since the pressing of the pressing member 82 is released,the sheet S can be moved in the conveyance direction.

After ACT 24, ACT 25 is executed.

ACT 25 to ACT 28 are the same as ACT 14 to ACT 16 in the secondembodiment, except that they are executed based on the control signalfrom the control circuit 62.

Thus, the image forming operation when the sheet S is fed from the sheetfeed cassette 81 is completed.

According to the image processing apparatus 102 of the presentembodiment, since the sheet feed cassette 81 includes the resistancemember 16 and the control circuit 62 that lifts and lowers the elevatingplate 202 to perform the separation, it is possible to prevent doublefeeding in the sheet supply unit 70 even if the user does not separatethe sheets S before placing the sheets S.

Hereinafter, modifications of the above-described embodiments will bedescribed.

FIG. 25A is a schematic diagram of a cross section showing amodification (first modification) of the resistance member in the sheetconveying device of each embodiment.

As shown in FIG. 25A, a resistance member 161 may be used instead of theresistance member 16 of each embodiment.

The resistance member 161 has a flat surface 1611 macroscopically but ismade of a material that has a large sliding resistance with the leadingend St of the sheet S.

For example, in the resistance member 161, the surface layer portionthat contacts the sheet S is formed of felt cloth. The surface 1611 ofthe resistance member 161 is a flat surface as a whole along thestacking direction H, but when viewed microscopically, the surface 1611is formed of a finely uneven surface in which fibers are randomlyentangled.

Therefore, as compared with a smooth surface such as resin or metal, thecoefficient of friction with respect to the sheet S is large, and thusthe sliding resistance with the leading end St of the sheet S is large.

If the sliding resistance becomes large, when the leading ends St of thesheets S move in the stacking direction H, the leading ends of thesheets S cause stick-slip, and are thus separated.

As a material that can increase the sliding resistance with the leadingend St of the sheet S even though the resistance member 161 has amacroscopically flat surface 1611, other than felt, for example, anelastomer, a foamed elastomer, cork, a non-woven fabric, or the like canbe used.

FIG. 25B is a schematic diagram of a cross section showing amodification (second modification) of the resistance member in the sheetconveying device of each embodiment.

As shown in FIG. 25B, a resistance member 162 may be used instead of theresistance member 16 of each embodiment. The surface 1621 of theresistance member 162 that contacts the sheet S has an uneven structure.

The resistance member 162 can be made of, for example, a synthetic resinor an elastomer having an uneven structure on the surface 1621. Examplesof the uneven structure include a corrugated shape in which unevennesschanges in the stacking direction H, and a mountain-shaped uneven shape.

If the uneven structure is formed on the surface 1621, when each leadingend St of the sheet S moves along the stacking direction H, the leadingend St vibrates when passing over the uneven structure, and is thusseparated.

FIG. 25C is a schematic diagram of a cross section showing amodification (third modification) of the resistance member in the sheetconveying device of each embodiment.

As shown in FIG. 25C, a resistance member 163 may be used instead of theresistance member 16 of each embodiment. Similar to the resistancemember 16, the resistance member 163 includes a napped material.However, the fibers 1631 in the napped material of the resistance member163 are inclined obliquely upward with respect to the stacking directionH.

Therefore, the sliding resistance of the resistance member 163 withrespect to the sheet S is higher when the sheet S is lowered than whenthe sheet S is lifted. As a result, the sheet S is separatedparticularly efficiently when descending.

FIG. 25D is a schematic diagram of a cross section showing amodification (fourth modification) of the regulation plate in the sheetconveying device of each embodiment.

As shown in FIG. 25D, a regulation plate 90 may be used instead of theregulation plate 15 or the front end wall 203 of each embodiment. Theregulation plate 90 has a protrusion 901 formed on the surface providedwith the resistance member 16 to be separated from the resistance member16 in the Y direction. A plurality of protrusions 901 are provided in arange in which the protrusions 901 can contact the leading end St of thesheet S that can be placed on the sheet conveying device.

The height T of the protrusion 901 is lower than the height t of theresistance member 16. The protrusion 901 has a rounded end at the distalend in the protruding direction to reduce sliding resistance with thesheet S.

Since the regulation plate 90 of this modification includes a pluralityof protrusions 901, the leading end St of the sheet S abuts theplurality of protrusions 901 when the sheet S is placed. Since thesheets S are guided by the protrusions 901 when the sheets S areseparated, the position of the leading ends St of the sheets S are lesslikely to vary.

According to the modification, since the leading end St of the sheet Sabuts each of the protrusions 901, the length by which the resistancemember 16 enters the sheet S is restricted to (t-T), and thus, thesliding resistance is stabilized.

FIG. 25E is a schematic diagram of a cross section showing amodification (fifth modification) of the resistance member in the sheetconveying device of each embodiment.

As shown in FIG. 25E, a resistance member 164 may be used instead of theresistance member 16 of each embodiment. A plurality of resistancemembers 164 are provided in the stacking direction H to be separatedfrom each other. The material and surface shape of the resistance member164 may be the same as those of the resistance member 16 and each of theabove-described modifications.

The number and arrangement interval of the resistance members 164 in theloading direction H are not particularly limited.

According to the resistance member 164 of the present modification, thestate of being in contact with the resistance member 164 and the stateof being not in contact with the resistance member 164 are repeatedwhile the sheet S is ascending and descending. When the sheet S is incontact with the resistance member 164, the sheet S receives slidingresistance, and when the sheet S is not in contact with the resistancemember 164, the sheet S does not receive sliding resistance, and thusthe change in sliding resistance along the stacking direction H islarge. As a result, in the modification, the sheet S can be separatedmore efficiently.

FIG. 25F is a schematic diagram of a modification (sixth modification)of the resistance member in the sheet conveying device of the firstembodiment as viewed from the conveyance direction.

As shown in FIG. 25F, a resistance member 165 may be used instead of theresistance member 16 of the first embodiment. While the resistancemember 16 is provided along the stacking direction H, the resistancemember 165 is arranged to be inclined toward the conveyance center lineM as advancing upward in the stacking direction H.

According to the resistance member 165 of the present modification,since the contact position with the resistance member 165 changes in theY direction while the sheet S moves up and down, the sheet S can beseparated more efficiently.

In particular, when the sheet S descends with a large separating force,since the sheet S is separated toward the outside in the width directionof the sheet S, both sides of the sheet S in the width direction arewell separated.

The modification may be applied to the second and third embodiments.

FIG. 25G is a schematic diagram of a modification (seventh modification)of the resistance member in the sheet conveying device of the firstembodiment as viewed from the conveyance direction.

As shown in FIG. 25G, a resistance member 166 may be used instead of theresistance member 16 of the first embodiment. While the resistancemember 16 has a constant width w along the stacking direction H, theresistance member 166 has a width that decreases toward the upper sidein the stacking direction H. In FIG. 25G, the resistance member 166 hasa triangular shape but may have a trapezoidal shape whose width becomesnarrower toward the upper side.

According to the resistance member 166 of the present modification,since the resistance member 166 and the width thereof become narrowertoward the upper side in the stacking direction H, the change in thesliding resistance between the ascending time and the descending time isdifferent.

In the modification, the sliding resistance is increased duringdescending when the separating force is increased, and therefore, theseparation is more strongly performed when descending.

The modification may be applied to the second and third embodiments.

In each embodiment, an example in which the sheet conveying device isused in an image processing apparatus that performs image formation isdescribed, but the sheet conveying device may be used in an imageprocessing apparatus that does not perform image formation. For example,the sheet conveying device may be used in an image processing apparatusthat erases an image formed with a decolorable toner by heating, lightirradiation, or the like.

The sheet conveying device may be used in an apparatus other than theimage processing apparatus as long as the apparatus uses sheets that arepreferably subjected to the separation.

In the first embodiment, an example of the elevating mechanism 40including a cam was described, but the elevating mechanism 40 is notlimited to a device configuration including a camas long as theelevating plate 13 can be lifted and lowered.

In the third embodiment, the example in which the lower space R isformed by the sheet feed cassette 81 having the inclined bottom surfaceportion 811 was described. However, the shape of the lower space R isnot particularly limited as long as the elevating plate 202 can descendto the second lowered position. For example, instead of the inclinedbottom surface portion 811, a stepped bottom surface portion lower thanthe bottom surface portion 201 may be provided.

An image processing apparatus and a sheet conveying device of amodification (eighth modification) of the second embodiment will bedescribed.

As shown in FIG. 1 , an image processing apparatus 103 according to themodification (eighth modification) of the second embodiment includes asheet supply unit 90 (sheet conveying device) and a control circuit 63instead of the sheet supply unit 70 and the control circuit 62 of theimage processing apparatus 102 according to the second embodiment. Thesheet supply unit 90 is an example of the sheet conveying deviceaccording to the modification of the second embodiment.

FIG. 26 is a schematic diagram of a cross section of a sheet conveyingdevice according to a modification (eighth modification) of the secondembodiment.

As shown in FIG. 26 , the sheet supply unit 90 is a tandem-type sheetfeeding device capable of arranging a first sheet bundle formed of aplurality of sheets S1 and a second sheet bundle formed of a pluralityof sheets S2. The first sheet bundle and the second sheet bundle areadjacent to each other in the conveyance direction of the cassette sheetfeed unit 21.

The conveyance direction in the cassette sheet feed unit 21 of thepresent modification is the Xp direction, as in the second embodiment.

The sheet supply unit 90 includes a sheet feed cassette 91 and a sheetbundle moving mechanism 96 (moving mechanism, elevating mechanism).

The sheet feed cassette 91 is a box type that opens in the Zp direction,similar to the sheet feed cassette 20 in the second embodiment. Thesheet feed cassette 91 has a bottom surface portion 911 and a pluralityof walls extending in the Zp direction from the outer edge of the bottomsurface portion 911.

On the bottom surface portion 911, an elevating plate 92 (tray) isarranged closer to the Xp direction side than the center in the Xdirection.

On the bottom surface portion 911, a guide unit 912 and a moving tray 93are arranged closer to the Xm direction side than the center in the Xdirection.

A plurality of sheets S1 or a plurality of sheets S2 transferred fromthe moving tray 93 described later can be placed on the elevating plate92. The elevating plate 92 is a flat plate extending parallel to the ZXplane. The elevating plate 92 is provided to be movable in parallel inthe Z direction in the space inside the sheet feed cassette 91 above theupper surface of the bottom surface portion 911. The elevating plate 92can be lifted and lowered between the lowest first lowered positionshown in FIG. 26 and the uppermost position where the upper surface cancontact the pickup roller 212.

The guide unit 912 is arranged on the bottom surface portion 911 andsupports the moving tray 93 from below. The guide unit 912 supports themoving tray 93 to be movable in the X direction. The guide unit 912supports the moving tray 93 to be movable in the X direction between afirst position displaced in the Xm direction (a direction opposite tothe conveyance direction) from the elevating range of the elevatingplate 92, and a second position above the elevating plate 92 that movedto the first lowered position.

The moving tray 93 supports a plurality of sheets S2 from below. Thesize of the sheet S2 that can be placed on the moving tray 93 is equalto or smaller than the maximum size of the sheet S1 that can be stackedon the elevating plate 92. The moving tray 93 is guided by the guideunit 912 and can reciprocate between the first position and the secondposition.

The plurality of walls include a front end wall 913 (regulation plate)instead of the front end wall 203 of the sheet feed cassette 20 in thesecond embodiment. The plurality of walls include two side walls 915instead of the front side wall 204 and the rear side wall 205 of thesheet feed cassette 20.

The front end wall 913 is similar to the front end wall 203, except thatthe conveyance guide plate 2031 is not included. The resistance member16 is provided on the surface of the front end wall 913 in the Xmdirection, as in the second embodiment. The front end wall 913 is anexample of a regulation plate that regulates the position of the leadingend of the sheet S1 in the conveyance direction.

The two side walls 915 are arranged with a space wider than the width ofthe elevating plate 92 and the moving tray 93 in the Y direction. Astopper 94 is arranged inside each side wall 915.

The stopper 94 is selectively switched between a state of advancinginward from the outside of the conveyance path of the moving tray 93 anda state of being retracted from the conveyance path.

When each stopper 94 advances, each stopper 94 abuts the ends of theplurality of sheets S1 on the elevating plate 92 in the Xm directionover the entire stacking direction. When the stoppers 94 are retracted,a space is provided between the stoppers 94 so that the moving tray 93and the plurality of sheets S2 moving together with the moving tray 93can pass through.

The configuration of the stopper 94 is not particularly limited. Forexample, the stopper 94 may be a plate movably supported in the Ydirection or a plate rotatably supported in the YZ plane.

The sheet bundle moving mechanism 96 moves the elevating plate 92, themoving tray 93, and each stopper 94 within their respective movableranges. The sheet bundle moving mechanism 96 includes a motor that liftsand lowers the elevating plate 202, and a drive transmission mechanismthat transmits the driving force of the motor to the elevating plate202. The sheet bundle moving mechanism 96 includes a motor that movesthe moving tray 93 in the X direction, and a drive transmissionmechanism that transmits the driving force of the motor to the movingtray 93. The sheet bundle moving mechanism 96 includes a motor or asolenoid that moves each stopper 94 forward and backward.

The sheet bundle moving mechanism 96 is communicatively connected to thecontrol circuit 63. The sheet bundle moving mechanism 96 drives theelevating plate 92, the moving tray 93, and each stopper 94 based on acontrol signal from the control circuit 63.

The sheet bundle moving mechanism 96 is an example of an elevatingmechanism that lifts and lowers the elevating plate 92 in the stackingdirection of the plurality of sheets S1.

The sheet bundle moving mechanism 96 is an example of a moving mechanismthat moves the moving tray 93 from the first position to the secondposition and places the plurality of sheets S2 on the elevating plate 92when the elevating plate 92 is descending.

Similar to the control circuit 61 in the second embodiment, the controlcircuit 63 controls the entire image processing apparatus 103. Thecontrol circuit 63 is the same as the control circuit 61 in the secondembodiment, except that the control circuit 63 transmits a controlsignal to the sheet bundle moving mechanism 96 to perform a transferoperation of transferring the plurality of sheets S2 on the moving tray93 onto the elevating plate 92.

However, the control circuit 63 transmits a control signal to the sheetbundle moving mechanism 96 to lift and lower the elevating plate 92,thereby causing the plurality of sheets arranged on the elevating plate92 to be separated.

The transfer operation will be briefly described. In the transferoperation, the control circuit 63 transmits a control signal to thesheet bundle moving mechanism 96 to perform the following operation.

When the control circuit 63 detects that all of the plurality of sheetsS1 were conveyed from the elevating plate 92 in the same manner as inthe second embodiment, the control circuit 63 lowers the elevating plate92 to the first lowered position and retracts the stoppers 94. Afterthat, the control circuit 63 moves the moving tray 93 from the firstposition to the second position. After that, the control circuit 63advances each stopper 94. Each stopper 94 is locked to the ends of theplurality of sheets S2 on the moving tray 93 in the Xm direction.

After that, the control circuit 63 moves the moving tray 93 from thesecond position to the first position. Here, since the ends of theplurality of sheets S2 in the Xm direction are supported by the stoppers94, only the moving tray 93 moves to the first position. The pluralityof sheets S2 drop onto the elevating plate 92.

Thus, the transfer operation is completed.

The separating operation in the sheet supply unit 90 is the same as thatin the second embodiment, except that the sheet bundle moving mechanism96 lifts and lowers the elevating plate 92 at least once between thefirst lowered position and the lifted position.

In the separating operation of the modification, the leading end St ofthe sheet arranged on the elevating plate 92 moves in parallel in the Zdirection in the state of being in contact with the resistance member16. Therefore, for example, even when the number of sheets stacked onthe elevating plate 92 is large, uniform separation is performed in thestacking direction.

The separating operation in the modification may be performed at anytime from when a plurality of sheets are arranged on the elevating plate92 to when the sheets are fed by the cassette sheet feed unit 21. Forexample, the control circuit 63 may execute the separating operationimmediately after the transfer is completed or may execute theseparating operation after receiving the print start signal.

According to at least one embodiment described above, since the sheetconveying device includes a tray that stacks a plurality of sheets, anelevating mechanism that lifts and lowers the tray in the stackingdirection of the plurality of sheets, a conveyance roller that conveysthe plurality of sheets in the conveyance direction from the upper sidein the stacking direction, and a resistance member imparting a slidingresistance larger than that of the sheet stacking surface of the tray tothe leading ends of the plurality of sheets that are lifted and loweredby the elevating mechanism, it is possible to provide a sheet conveyingdevice capable of preventing double feeding even if the user does notseparate a plurality of sheets before placing the sheets S.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of the inventions. Indeed, the novel embodiments described hereinmay be embodied in a variety of other forms: furthermore, variousomissions, substitutions and changes in the form of the embodimentsdescribed herein may be made without departing from the spirit of theinventions. The accompanying claims and their equivalents are intendedto cover such forms or modifications as would fall within the scope andspirit of the inventions.

What is claimed is:
 1. A sheet conveying device, comprising: a trayconfigured to accommodate a stack of a plurality of sheets; an elevatingmechanism configured to lift and lower the tray in a stacking directionof the plurality of sheets; a conveyance roller configured to convey onesheet at a time from the plurality of sheets in the conveyance directionfrom the upper side in the stacking direction; a resistance member incontact with a leading end of the plurality of sheets in the conveyancedirection and configured to impart a sliding resistance larger than asliding resistance of a sheet stacking surface of the tray to theleading ends of the plurality of sheets that are lifted and lowered bythe elevating mechanism; and an actuator configured to rotate whenpushed by a leading end of the sheet, wherein the resistance memberarranged on both sides of a conveyance center line in the sheet transferdevice, and the actuator located between the resistance member arrangedon both sides of the conveyance center line.
 2. The device according toclaim 1, wherein the resistance member comprises a surface layer portionthat comes into contact with the plurality of sheets and the surfacelayer portion is non-smooth in the stacking direction.
 3. The deviceaccording to claim 2, wherein the resistance member has a nappedmaterial comprising a plurality of fibers extending toward the pluralityof sheets on the surface layer portion.
 4. The device according to claim1, wherein the resistance member has a surface in contact with theplurality of sheets and the surface has a friction coefficient largerthan a friction coefficient of the sheet stacking surface.
 5. The deviceaccording to claim 1, wherein the resistance member has conductivity. 6.The device according to claim 1, wherein the elevating mechanism liftsand lowers the tray between a first lowered position where the pluralityof sheets is set and a lifted position above the first lowered positionin the stacking direction and capable of abutting upper ends of theplurality of sheets against the conveyance roller, and the resistancemember is arranged at a position contacting the leading end of theplurality of sheets in at least a part of the elevating range of thetray.
 7. The device according to claim 6, wherein the elevatingmechanism configured to descend to a second lowered position locatedbelow the first lowered position in the stacking direction and move thetray from the second lowered position toward the lifted position.
 8. Thedevice according to claim 1, wherein the tray stacks a first sheetbundle comprising a plurality of sheets so that the leading end of thefirst sheet bundle abuts the resistance member and the first sheetbundle can be lifted and lowered, and the device further comprises amoving tray configured to be movable between a first position in thedirection opposite to the conveyance direction with respect to the trayand a second position on the upper side of the tray to place a secondsheet bundle formed of a plurality of sheets, and a moving mechanismconfigured to move the moving tray from the first position to the secondposition and place the second sheet bundle on the tray when the tray isdescending by the elevating mechanism.
 9. The device according to claim6, further comprising: a control circuit configured to control theconveyance roller and the elevating mechanism, wherein the controlcircuit causes the elevating mechanism to lift and lower the tray atleast once in an elevating range in which the plurality of sheets comeinto contact with the resistance member and then to move the tray to thelifted position, and then, drive the conveyance roller to start theconveyance of the plurality of sheets.
 10. An image processingapparatus, comprising: an image forming device; and a sheet conveyingdevice comprising: a tray configured to accommodate a stack of aplurality of sheets; an elevating mechanism configured to lift and lowerthe tray in a stacking direction of the plurality of sheets; aconveyance roller configured to convey one sheet at a time from theplurality of sheets in the conveyance direction from the upper side inthe stacking direction; a resistance member in contact with a leadingend of the plurality of sheets in the conveyance direction andconfigured to impart a sliding resistance larger than a slidingresistance of a sheet stacking surface of the tray to the leading endsof the plurality of sheets that are lifted and lowered by the elevatingmechanism; and an actuator configured to rotate when pushed by a leadingend of the sheet, wherein the resistance member arranged on both sidesof a conveyance center line in the sheet transfer device, and theactuator located between the resistance member arranged on both sides ofthe conveyance center line.
 11. The apparatus according to claim 10,wherein the resistance member comprises a surface layer portion thatcomes into contact with the plurality of sheets and the surface layerportion is non-smooth in the stacking direction, the resistance memberhas a napped material comprising a plurality of fibers extending towardthe plurality of sheets on the surface layer portion.
 12. The apparatusaccording to claim 10, wherein the resistance member has a surface incontact with the plurality of sheets and the surface has a frictioncoefficient larger than a friction coefficient of the sheet stackingsurface.
 13. A sheet conveying method, comprising: lifting and loweringa tray configured to accommodate a stack of a plurality of sheets in astacking direction of the plurality of sheets using an elevatingmechanism; conveying one sheet at a time from the plurality of sheets inthe conveyance direction from the upper side in the stacking direction;contacting a resistance member with a leading end of the plurality ofsheets in the conveyance direction and imparting a sliding resistancelarger than a sliding resistance of a sheet stacking surface of the trayto the leading ends of the plurality of sheets that are lifted andlowered by the elevating mechanism; and rotating an actuator when pushedby a leading end of the sheet, wherein the resistance member arranged onboth sides of a conveyance center line in the sheet transfer device, andthe actuator located between the resistance member arranged on bothsides of the conveyance center line.
 14. The method according to claim13, wherein the resistance member comprises a surface layer portion thatcomes into contact with the plurality of sheets and the surface layerportion is non-smooth in the stacking direction.
 15. The methodaccording to claim 14, wherein the resistance member has a nappedmaterial comprising a plurality of fibers extending toward the pluralityof sheets on the surface layer portion.
 16. The method according toclaim 13, wherein the resistance member has a surface in contact withthe plurality of sheets and the surface has a friction coefficientlarger than a friction coefficient of the sheet stacking surface. 17.The method according to claim 13, further comprising: lifting andlowering the tray between a first lowered position where the pluralityof sheets is set and a lifted position above the first lowered positionin the stacking direction and abutting upper ends of the plurality ofsheets against the conveyance roller; and contacting the leading end ofthe plurality of sheets in at least a part of the elevating range of thetray.
 18. The method according to claim 17, further comprising:descending the elevating mechanism to a second lowered position locatedbelow the first lowered position in the stacking direction and movingthe tray from the second lowered position toward the lifted position.19. The method according to claim 13, wherein the tray stacks a firstsheet bundle comprising a plurality of sheets so that the leading end ofthe first sheet bundle abuts the resistance member and the first sheetbundle can be lifted and lowered, and further comprising: moving amoving tray between a first position in the direction opposite to theconveyance direction with respect to the tray and a second position onthe upper side of the tray to place a second sheet bundle formed of aplurality of sheets; and moving the moving tray from the first positionto the second position and placing the second sheet bundle on the traywhen the tray is descending.
 20. The method according to claim 17,further comprising: lifting and lowering the tray at least once in anelevating range in which the plurality of sheets come into contact withthe resistance member and then moving the tray to the lifted position,and then, driving the conveyance roller to start the conveyance of theplurality of sheets.